DSI is well worth the money, especially if you have to go outside just before a shower to ignite a pilot. Plus, you will not be wasting propane while he pilot is lit.
If you want the best (IMHO)water heater, look at the Precision Temp RV-500. It has no tank to keep hot and heats the water instantly. It will give you as much hot water as you want, limited only by the amount of propane available.
I replaced the 6 gal. that came with my 19CCD and had to do a little 'surgery' to the skins as well. It is not a problem if you are careful and precise in your measuring.
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician
SOLAR TECH ENERGY SYSTEMS, INC.
AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION